Radiation therapy involves medical procedures that selectively expose certain areas of a human body, such as cancerous tumors, to high doses of radiation. The intent of the radiation therapy is to irradiate the targeted biological tissue such that the harmful tissue is destroyed. During a radiation therapy, a radiation source may be rotated around a patient to deliver radiation from different angles at target region inside the patient. The radiation source may be mounted on an arm or a ring gantry. In certain radiation therapy, the patient support supporting the patient may also be moved. Despite careful treatment planning, during a medical procedure, a collision may occur between a moving part of a medical device and a patient. For example, the gantry of the radiation machine and the patient may possibly collide during radiation therapy. As the dose delivery plans become more complex, the combination of a rotating gantry during treatment and couch movement for non-coplanar beams delivery increases the chance of collisions.
One technique to avoid collision between the patient and the radiation machine is to use a depth camera, which detects the surface of the patient. The detected surface forms a model representing the object that is desired to be protected. The model may then be used to monitor a proximity of components of the radiation machine relative to a boundary of the model to determine if a collision is imminent.
Systems and methods for accurately determining the position and orientation of a depth camera relative to a certain coordinate system are described herein. By accurately determining the position and orientation of the depth camera, information derived from the depth camera can then be transformed accurately to a desired coordinate system.